1. Field of the Invention
This information relates generally to exercise apparatus, and more particularly to exercise apparatus for strengthening the arms, fingers, and wrists.
2. Description of the Prior Art
The prior art teaches a number of devices for exercising the wrist and/or forearm. For example, in U.S. Pat. No. 4,039,183 of Sakurada, a device for exercising and strengthening the human wrist is disclosed which includes a concave member having two parallel, spaced members projecting from one thereof, and a grip rotatably mounted between the ends of the spaced members. Springs provide a force which rotate the grip away from the longitudinal axis of the concave member. The device fits upon a user's forearm directly above the wrist and provides wrist strengthening exercises.
In U.S. Pat. No. 440,837 of Bonelli, an exercising device for musicians is taught including an elongated lever pivotally attached to one end of the base and provided with a grip at its other end. A musician rests his arm against a support plate positioned above the elongated lever, and exercises his fingers and wrist by pressing upwardly on the grip to raise the lever against spring pressure.
U.S. Pat. No. 4,310,154 of Kauffman teaches a device for exercising the fingers, wrist, and forearm including an elongated, rigid body member arranged to receive a person's wrist and at least a portion of the forearm. A grip member is pivotally attached to the front of the body member and is urged to an upward angular position with relation to the body member by springs. A pair of straps are used to attach the body member to the user's forearm so that the fingers, wrist, and forearm may be exercised by repeatedly pivoting the grip member against the spring pressure.
It is desirable to be able to conveniently vary the force exerted by the springs of an exercise device so that as the user's strength increases, the resistance force may likewise be increased. Unfortunately, in the prior art the spring force of forearm and wrist exercisers has been difficult or impossible to increase.
Furthermore, most wrist and forearm exercisers of the prior art utilize two springs (i.e. one for each leg of a pivoting grip member) which creates problems of force equalization between the two springs. For example, if one spring were stronger than the other, the grip would tend to twist rather than smoothly pivot.